Mercury Grand Marquis:

no check engine light wont crank good fuel pump

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# 1  9/1/2015 6:15 PM

New member
Registered: 9/1/2015
Posts: 1

no check engine light wont crank good fuel pump

ok 2000 grand marquis gs I try to crank car no start and no check engine light then I hooked a live wire from batt to see if fuel pump came to the pcm relay box ..the check engine light came on and car started and ran but when removed the wire it stalled and died.checked all fuses all over the car all seem fine. radio and windows works everything but the check engine light and engine starting is good . ran the car with wire but runs crappy and scared its gonna mess something else up please help



# 2  9/2/2015 12:05 AM

Registered: 11/24/2009
Posts: 1299

Re: no check engine light wont crank good fuel pump

According to the wire schematic, fuse #1 in the battery junction box is the main feed for the fuel pump. It supplies 12V to the fuel pump relay; the relay is operated by the PCM. When the PCM sees all the data it needs to run the engine the PCM supplies a ground for the fuel pump relay. From the fuel pump relay the 12V travels to a switch called an inertia fuel cut off. You need 12V on both sides of this switch. If you only have 12V on one side you may have to reset the switch by pressing in the button on it. It can be found in the trunk on the drivers side (left side) behind the panel of the trunk. 12V goes from the inertia switch to the fuel pump.

The car ran so it would rule out ignition and a mechanical fault. You should have a professional mechanic put a scanner on the vehicle to see if you have an issue with the check engine light or if any codes are set. When you don't have a check engine light on with the key on and engine off it could be related to a data line problem usually associated with a problem with the PCM or data line wiring.

I am sending a schematic of the fuel pump circuit. I hope this helps you.
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